Densest* and least dense metals. 0.500g of lithium compared with 0.500g of iridium.
* It is well known that the lightest metal is lithium. There are two opinions regarding the heaviest one: some of the literature gives the title to osmium, some give it to iridium.
Theoretical calculation gave the following results (The lattice parameters, densities and atomic volumes of the platinum metals. Crabtree, Robert H. Sterling Chem. Lab., Yale Univ., New Haven, CT, USA. Journal of the Less-Common Metals (1979), 64(1), P7-P9. ) : "For Ru, Rh, Pd, Os, Ir, and Pt, the densities and atomic volumes were calculated by using lattice parameters obtained by averaging the best available values from the literature and correcting to 20°C by using a published relation for the lattice-parameter temperature dependence. The calculated densities of Os and Ir (22.59 ± 0.02 and 22.57 ± 0.01 g/cm3, respectively) are essentially equal within the probable experimental error." Certainly, in order to feel the difference between the densities of these two metals, it would be great to compare pieces of the exact same size and compare their weight. But lithium oxidizes readily in air and thus cannot be “weighed” with the hand. The large example of Ir is very expensive! So, to make the comparison, I decided to cut out pieces with identical weight.